After Fengel died in T.A. 2953, Thengel was called upon to return to Rohan, which he reluctantly did. During Thengel's reign, a mysterious Northerner calling himself Thorongil entered his service, and rode with him for some time. Saruman took Isengard for himself and began to fortify it.

Thengel had learned Sindarin while living in Gondor, and in his house it was the daily tongue, together with Westron, the common speech. Rohirric was not spoken by him or his heirs.